Forest History in East Africa's Eastern Arc Mountains: Biological Science and the Uses of History

Abstract

¡n this article, I argue that conservation science in its role of advocate for the natural world could profitably draw from site-speciflc histories that integrate huntan and natural histories. Both fields analyze the dynamic interaction of structure and process. In East Africa's Eastern Arc Mountains, where forests contain high levels of species endemism and biological diversity, the prevailing historical paradigm from conservation science represents today's forests as surviving fragments of much larger forests. This view builds upon a century-long tradition of scientific scholarship that has developed theories for the evolution of Eastern Arc forests that encompass geological time scales. However, the relatively brief millennialscale land-use history of the mountains, insofar as it is currently understood, suggests that human manipulation of forest biota involved periods of deforestation and regeneration, as well as the introduction of exotic plants.

Local factors mediate the response of biodiversity to land use on two African mountains

“…The greater Kilimanjaro area and the Taita Hills have been used by humans for many centuries (Heckmann et al ., ). Expeditions undertaken by German missionaries visiting Mount Kilimanjaro noted that the land was already extensively used in the 19th century (Börjeson, ) and similar evidence suggests that the agricultural terraces of the Taita Hills are centuries old (Conte, ). These sources indicate that both landscapes have experienced human influence for many centuries.…”

“…). Both landscapes are known for their long history of human modification (Conte, ; Heckmann et al ., ), while having a contrasting geological age (~30 Myr for Taita compared to ~2 Myr for Kilimanjaro, see Platts et al ., ), and each has different sets of endemic species (Hemp, ; Burgess et al ., ). Data on bird species richness and abundance were collected visually and audibly using standardized 10‐min fixed time point counts (Bibby et al ., ), of 50‐m radius, along each of the transects.…”

Climate Change and Forest Dynamics: A Soils Perspective

“…From Conte, 202 ''A forest understood as an agrarian landscape can include many centuries of forest-based husbandry.'' 203,204 For centuries, farmers in the eastern Arc Mountains of Africa used agroforestry in the mountains to cultivate native and introduced plants.…”

“…Kisagau, traditional botanical knowledge is tightly connected to a 1000 m elevation gradient and conveyed to generations through oral history that details the agro-ecological use of the entire mountain. 202 Farming once entailed a mosaic of forest ecosystems at varying stages of exploitation and regeneration that emphasised mobility, since water rather than temperature was a key factor of tree migration across Africa. 210 Farmers combined imported grain species with African beans, sorghum and millet, 211,212 and there is evidence that Asian banana was possibly a feature in African agroforestry for more than 5000 years.…”

Records of Arthropod Species Sampled from Avocado Plant (Persea americana Mill) in Small-scale Agro-ecosystems at Taita Hills and Mount Kilimanjaro

“…Such ecosystems are located near indigenous forests with favourable agricultural conditions as exemplified by Afrotropical highlands at Mount Kilimanjaro and Taita Hills where avocado is the dominant fruit crop (Griesbach, 2005;Wasilwa et al, 2004). However, the potential land area available for avocado farming along slopes of Mount Kilimanjaro in Northeastern Tanzania and Taita Hills in South-eastern Kenya is shrinking as a result of ecological degradation (Conte, 2010) and human activities. The envisaged reduction of avocado orchards in these East African highlands will not only affect distribution of arthropod species but also livelihood of local farmers that depend on avocado fruits as a source of cash and nutritious food (Hemp, 2009).…”